The EU chemicals legislation consists of the Regulation on Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) and the Regulation on Classification, Labelling, and Packaging of Substances and Mixtures (CLP), complemented by over fifty regulations and directives regulating specific uses and products. While regulating individual uses may offer a faster and simpler approach to protecting human health and the environment from hazardous chemicals, it can also lead to inconsistencies, such as gaps and overlaps. These inconsistencies may arise for chemicals with multiple uses, each governed by separate legislation.

The overall objective of this work was to understand the links between different pieces of EU chemicals legislation, to identify inconsistencies in the regulation of chemicals covered by multiple regulations and, in particular, to explore the implications of these inconsistencies for the protection of human health and the environment. First, we compared how antimicrobial substances are regulated when used in biocidal products compared to cosmetics (Paper I). The risk assessment of cosmetic preservatives focused solely on human health, omitting environmental data and environmental risk assessment. Once granted, the approval of cosmetic preservatives remained valid indefinitely until revoked by the European Commission, with no requirement to update the dossier based on new information. Based on these findings, we examined whether the approved cosmetic preservatives were hazardous to the aquatic environment or persistent, and if so, whether the risks were efficiently managed by REACH (Paper II). The analysis showed that environmental hazards of cosmetic preservatives and other ingredients are overlooked by the Cosmetic Products Regulation and might not be effectively managed by REACH. Next, the linkage between the CLP and other pieces of chemicals legislation was examined, mapping out regulatory obligations, arising from the new CLP hazard classes for endocrine disruption for human health (ED HH), endocrine disruption for the environment (ED ENV), PBT/vPvB, and PMT/vPvM (Papers III and IV). Meeting criteria for human health hazards under the CLP triggered more regulatory obligations across multiple regulations, compared to when fulfilling the criteria for physical or environmental hazards. Implementation of the new CLP hazard classes will require revision of regulations with existing risk management measures connected to the CLP hazard criteria.

The results and conclusions of the studies included in this thesis highlight the need for addressing the existing inconsistencies in order to strengthen the protection of human health and the environment. The provided recommendations address the need for harmonisation of the chemicals legislation and more efficient management of hazardous chemicals.